1. Field of the Invention
The present invention relates to a connector for connecting leads to a housing for an implantable pacer.
2. Description of the Prior Art
A pacer system normally comprises a pulse generator located in a pacer housing, leads and electrodes at the distal end of the leads. The proximal end of the leads is connected to the pacer housing by means of a releasable connector. The connector comprises a female connector part in the pacer housing. The proximal end of the lead normally is designed as a standardized male connector part and the female connector part normally is standardized to such an extent that it will receive this standardized male connector part. The most common way of fixing or locking the male connector part in the female connector part is to use set screws which are oriented in an orthogonal direction in relation to the male connector part and which are accessible from the outside of the pacer housing. The female connector part normally is located in a header molded on to the housing.
While these setscrews generally have a good fixing effect, the screws are somewhat difficult to handle, the screws being small. For this reason, attempts have been made to develop fixing means, which more or less automatically lock the male connector part upon insertion thereof.
One such device is for instance disclosed in U.S. Pat. No. 5,252,090. This device includes two elastically resilient metal tongues in a female connector part. The tongues are situated in a common plane and have a common central line, with a respective free end, which are located oppositely to each other. The distance between the two free ends is smaller than the diameter of the male connector part. The tongues will be deflected into the direction of insertion when the male connector part is inserted into the female connector part and the tongues thus will engage and lock the sides of the male connector part. If the male connector part is pulled outwardly from the female connector part, the locking effect will increase. The reason is that the friction between the tongues and the male connector part will draw the tongues in closer contact with the male connector part. The two tongues are integrally connected to two wings extending through openings in the header. The wings are angled in relation to the plan of the tongues. Pressure on the wings will move the tongues out of engagement with the male connector part, which then can be removed.
In similarity with the design using setscrews, the locking means in the above design have to be accessed laterally from the outside. For this reason, the locking means are located in the header in order to avoid openings for manipulation in the parts of the housing in which the electronic parts of the pacer are located. Any openings for the connections in the housing or can into the interior of the housing from the header can be permanently sealed.
Another design of a device for locking the terminal pin of a male connector plug is disclosed in U.S. Pat. No. 4,784,141. This device is designed for location in one open end of a bore through a header or through the pacer and is accessible from that end. The male plug is to be inserted through the opposite end of the bore. The locking device comprises a hollow cylindrical part with interior threads and an interior, end flange with a conical interior surface. The locking device further comprises a plug with a central bore and with external threads fitting the interior threads in the cylindrical part. The inner open end of the plug is also provided with a conical surface. A resilient locking ring with conically shaped sides is located between the respective conical surface on the plug and on the cylindrical part. When the plug is screwed inwardly into the cylindrical part, the conical surfaces on plug and cylindrical part will compress the locking ring inwardly against a connector pin inserted into the locking part. In this way the pin is locked in the locking device.